The instant invention relates to apparatus of the type used for stranding wires or filaments and more particularly to an apparatus and method for twisting wires or filaments to form a cable of unlimited length.
It is well recognized that flexible cables of the type comprising a plurality of wire elements which are twisted into a cable are highly effective for many electrical conductor and cable applications. For this reason, various types of apparatus have been developed over the years for twisting elements to form stranded cables. In this regard, one of the most common types of heretofore available machines of this general type is disclosed in the U.S. Pat. No. 2,817,948 to COOK. The device disclosed in this patent operates by feeding a plurality of wires to a rotating closing die where they are twisted around a core wire to form a cable. The cable is then passed to a rotating flyer which is also mounted in coaxial relation to the closing die so that it travels around a rotating reel which is mounted in coaxial relation to the closing die. The cable then passes from the flyer to the reel, and it is wound on the reel at a rate which is determined by the difference between the rate of rotation of the flyer and the rate of rotation of the reel. Actually, the difference between the rate of rotation of the flyer and the rate of rotation of the reel also controls the rate at which stranded cable is produced from the apparatus, since it controls the rate at which cable is drawn through the closing die. Further, since the closing die and the flyer rotate together, the difference between the rate of rotation of the flyer and the rate of rotation of the reel actually also controls the length of twist in the finished cable. For example, if cable is drawn through the closing die at an increased rate without increasing the rate of rotation of the flyer and the closing die, the length of each twist in the finished cable is increased correspondingly. However, since the rate at which cable is drawn through the closing die is also dependent on the winding diameter of the reel which varies as cable is wound thereon, conventional machines of this type have generally included a control apparatus for controlling the difference between the speed of the flyer and the speed of the reel to maintain a constant length of twist in the finished cable. An early control apparatus of this general type is disclosed in the U.S. Pat. No. 2,929,193 to COOK, and a more sophisticated digital electronic control device of this general type is currently manufactured and marketed by Cook Machinery Division of the Entwistle Company, of Hudson, Mass., as the "Cook Acculay Digital Lay Control System".
While wire twisting machines of the above described type have been effectively utilized for many years to form stranded cables at relatively high production rates, it has not been possible to form stranded cables of infinite lengths with machines of this type. This is because the maximum length of a cable which can be produced from a machine of this type is dictated by the size of the take-up reel or spool on which the finished product is wound. In this connection, since a machine of this type operates with a flyer which rotates around a take-up reel, it is not possible to replace or refill the take-up reel without completely removing and disconnecting the finished reel and the cable from the machine. Further, since it is not considered to be acceptable practice to weld two cables together by welding the individual strands thereof together unless the individual welds are spaced at different points along the extent of the composite cable, it has generally not been practical or even possible to weld two stranded cables together to form a single high-quality cable of increased length with a machine of this type.
The instant invention provides an effective method and apparatus which can be operated at high speeds for producing cables of infinite lengths. Specifically, in its preferred embodiment, the apparatus of the instant invention is operative for twisting a wire element or a filament on an advancing core, and it comprises a reel mounted for rotation about an axis and having a wire element wound thereon, a flyer mounted for rotation about the axis so that it travels around the reel and engages the wire element for unwinding it from the reel, means for rotating the reel about its axis, and means for rotating the flyer about its axis in the same direction as the reel but at a speed which causes the wire element to be unwound from the reel by the flyer. The apparatus further comprises gathering means rotating about the axis of the reel with the flyer for gathering the wire element therefrom and for twisting it around the core element as the core element is passed axially through the gathering means to form a cable. In addition, the apparatus comprises means for drawing the cable from the gathering means, means for measuring the number of rotations of the flyer and the gathering means per unit length of cable, and means for controlling and adjusting the rotational speed of the flyer relative to the rotational speed of the reel to achieve a substantially uniform number of rotations of the reel per unit length of cable so that the cable has a substantially uniform length of twist. Accordingly, during operation of the apparatus in accordance with the method, a wire element is unwound from the reel and wound onto the core as the core and the wire element pass through the gathering means, and the means for controlling and adjusting the rotational speed of the flyer relative to the rotational speed of the reel operates to achieve a substantially uniform length of twist in the cable even though the winding diameter of the reel is gradually reduced as the wire element is unwound therefrom. The apparatus is preferably constructed so that it is operative for simultaneously twisting a plurality of groups of wires onto a central core wire. Accordingly, the apparatus preferably includes first and second reels which are rotatably mounted about a common axis and which have first and second groups of side-by-side wires, respectively, wound thereon. The apparatus preferably further comprises first and second flyers which are mounted for rotation around the reels for unwinding the first and second groups of wires, respectively, therefrom and the gathering means is preferably operative for aligning different wires of the different groups in different spaced positions around the core wire and for twisting them around the core wire to form a cable. The first and second flyers are preferably disposed in substantially opposite radial positions relative to the axis of the reels, and the gathering means is preferably operative for aligning the wires from the first group in spaced relation on the same side of the axis as the first flyer and for aligning the wires from the second group in spaced relation on the same side of the axis as the second flyer. The apparatus is preferably constructed so that the flyer rotating means and the reel rotating means are independent of the means for drawing the cable from the gathering means, and the means for drawing the cable from the gathering means is preferably operative without significantly affecting the rotational speeds of the flyer and the reel. Further, the gathering means is preferably embodied as a closing die for twisting the wires around the core. In addition, the apparatus preferably also comprises means for determining the number of revolutions of the flyer relative to the reel in order to determine the amount of wire element left on the reel, and the means for rotating the reel is preferably reversible to enable it to be utilized for rewinding one or more additional wires thereon after it has been emptied. Still further, while the apparatus is normally operated for twisting filaments or wires around an advancing core wire or filament, it will be understood that it can also be operated for twisting two or more filaments or wires together to form a cable without a core wire or filament. Applications of this type are generally required to form cables having quantities of strands or filaments which do not readily lend themselves to normal symmetrical cable configurations, as is well known in the wire and cable industry.
Accordingly, during use and operation of the apparatus of the instant invention in accordance with the method of the instant invention, groups of wires are unwound from the reels by the flyers, and the wires are either twisted onto an advancing core wire or twisted together to form a stranded cable. In this connection, since the apparatus includes means for measuring the number of rotations of the flyer per unit length of cable and for controlling and adjusting the rotational speed of the flyer relative to the rotational speed of the reel to achieve a substantially uniform number of rotations of the flyer per unit length of cable, it is possible to make a cable having a uniform length of twist throughout its entire extent even though the wound diameters of the reels with the wires thereon are gradually reduced as the wires are unwound. Further, when all of the wires have been unwound from the reels, it is possible to wind new groups of wires onto the reels and to weld the ends of the new wires to the ends of the original wires so that the different welds in each group are located in longitudinally spaced locations. Accordingly, when the wires are twisted around the core wire or wound together, the welds are located in longitudinally spaced positions in the cable, and by joining the wires together in this manner, it is possible to construct a high-quality cable of unlimited length with the apparatus of the instant invention.
Devices representing the closest prior art to the instant invention of which the applicant is aware are disclosed in the U.S. Pat. Nos. 1,579,709 to Janicki; 1,734,704 Yancey, 2,200,955 2,365,277; Keating; 2,365,661 Winslow; 2,602,281 Bunch; 2,782,138 Olson et al; 3,077,068 Miller and 3,115,742 Ege. However, these references fail to suggest a wire twisting apparatus wherein wire is unwound from a reel by a flyer and then twisted to form a cable and wherein the speed of the flyer relative to the speed of the reel is controlled and adjusted to produce a cable having a substantially uniform length of twist. They also fail to suggest a wire twisting apparatus wherein groups of wires are unwound from several different reels or reel sections and then wound onto gathering means comprising a core wire with a closing die. They also fail to suggest a wire twisting apparatus comprising means for rotating the flyer and means for rotating the reel which are independent of the means for drawing cable from the gathering means and wherein the means for drawing cable from the gathering means operates without significantly affecting the rotational speeds of the flyer and/or the reel. Hence, for these reasons, the above references are believed to be of only general interest with respect to the instant invention.
Accordingly, it is a primary object of the instant invention to provide an effective wire twisting apparatus which is capable of producing twisted cables of unlimited lengths.
Another object of the instant invention is to provide an effective wire twisting apparatus which is operative for producing twisted cables of unlimited lengths having substantially uniform lengths of twist throughout their extents.
Another object of the instant invention is to provide an effective apparatus for producing twisted cables of unlimited lengths at high-production rates.
A still further object of the instant invention is to provide an effective method of forming a twisted cable of unlimited length.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.